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What is a percentage calculator?
A percentage expresses a number as a fraction of 100. Percentages appear in almost every business and financial context — revenue growth, budget allocation, discount pricing, commission rates, and investment returns. This calculator handles the four most common percentage problems in one place, with results explained in plain language rather than just a raw number.
How to use this percentage calculator
Percentage of a number. Enter a percentage and a base value to find the result. For example, 15% of $200 is $30. Use this to calculate tips, commissions, discounts, or any portion of a total.
Find the percentage. Enter two values to find what percentage the first is of the second. For example, $45 out of $180 equals 25%. Use this to track conversion rates, budget shares, or goal completion.
Percentage change. Enter an initial and a final value to find the increase or decrease between them. For example, revenue that grew from $4,000 to $5,500 represents a 37.5% increase — a gain of $1,500. This is the most common business use case for a percentage change calculator: month-over-month revenue, salary adjustments, and price comparisons.
Find the original number. Enter a partial value and the percentage it represents to reverse-calculate the base. For example, if 30 is 15% of a number, the original is 200. Use this to recover the price before a discount was applied.
Percentage formulas
How to calculate percentage change
Percentage change measures how much a value increased or decreased relative to its starting point. The formula is (New − Old) / Old × 100. A positive result means an increase; a negative result means a decrease.
For example, if a product cost $40 last year and costs $52 now, the percentage increase is ($52 − $40) / $40 × 100 = 30%. If a stock dropped from $150 to $120, the percentage decrease is ($120 − $150) / $150 × 100 = −20%. The calculator shows both the percentage and the absolute difference so you can see the full picture at once.
Everyday use cases
A freelancer raising rates from $85 to $110 per hour has increased their rate by 29.4%. A marketing team that spent $12,000 out of a $60,000 budget has used 20% of the total. A product priced at $89.99 with a 20% discount saves the buyer $18.00. Each of these is a one-step calculation — enter two numbers and the result appears immediately.
For pricing decisions, the percentage change mode shows how costs and selling prices shift over time. The Profit Margin Calculator covers the next step: once you know the revenue and cost numbers, it tells you whether the margin is healthy.